[en] We have run computer simulation in SU(2) lattice gauge theory on a 8³x2 lattice including dynamical quark loops. No rapid variation is observed in the value of Polyakov line, while the energy densities of quark and gluon show strong indication of a second order phase transition around T asymptotically equals 250MeV. In order to reduce finite size effects, the results are compared with those of free gas on a lattice of the same size. The quark and gluon energy densities overshoot the free gas values at high temperature. The effects of chemical potential is also studied. The behavior of the energy densities and the number densities are far from a free gas case. (author)

[en] QCDimMPI is a simulation code for pure SU(3) gauge theory with an improved action consisting of 1 x 1 and 2 x 1 plaquettes. It uses Fortran77 and the Message Passing Interface Standard, MPI[2]. QCDimMPI is an extended version of QCDMPI. It is portable, allows simulations in any number of dimensions, on any number of processors, and with arbitrary dimensional partitioning. It requires a rather small working area, and yields excellent performance on single processor computers and a wide variety of parallel computers which support MPI. The program provides information on link update time and communications time. In this paper, an outline of QCDimMPI is given, and benchmark results on several parallel computers are reported

[en] Using two-color lattice QCD with Wilson fermions, we report a study of the finite baryon number density system with two-flavors. First we investigate the Polyakov line and thermodynamical quantities in the (κ,μ) plane, where κ and μ are the hopping parameter and chemical potential in the fermion action, respectively. Then we calculate propagators of meson (q-bar Γq) and baryon (qΓq) states. We find that the vector meson propagators are strongly modified in large μ regions, indicating the reduction of the mass. This anomalous behavior of the vector meson is observed for the first time in lattice QCD

[en] Once the quark chemical potential μ is introduced in finite density QCD, the fermion determinant appeared in the path integral measure becomes complex. In order to investigate the phase effect of SU(3) lattice QCD (2-flavors), we calculated the fluctuation of the phase of det Δ(μ) on a 8³ x 4 lattice at μ = 0.1 and 0.2. Then we calculated the chiral condensate and Polyakov line in the no phase and reweighted cases. There is little difference between these two cases at μ = 0.1 and 0.2. We consider a possible reason for this result below μ ≤ 0.27 in terms of Z₃ symmetry

[en] We report our recent numerical studies on two-color QCD with Wilson fermions. First the phase structure of the system in (κ, μ)-plane is analyzed by measuring Polyakov line, baryon number density, gluon energy density and Polyakov line susceptibility. Then meson and baryon (di-quark) propagators are investigated. We find that the vector meson mass decreases near μ_c. This phenomena can be related to the low-mass lepton-pair enhancement observed in CERES experiment. Since our lattice is small, in order to confirm the results, we calculate both periodic and anti-periodic boundary condition cases. Preliminary calculations of color averaged, symmetric and anti-symmetric forces of qq system obtained from Polyakov line correlations, and gluon propagators are reported

[en] We study the change of the meson and diquark propagators in a high density state of the two-color QCD with a Wilson fermion. Both Wilson gauge action and Iwasaki improved action are investigated. In order to explore the high density frontier of the phase space, we adopt an exact algorithm based on Woodbury formula which is quite robust but heavy. Lattice size is 4³ x 8, a coupling is β = 0.70 and hopping parameter κ is 0.150 ∼ 0.175 for the Iwasaki improved action. In any case of our simulation, the vector meson only reveals strange rising up with large chemical potential[1]

[en] We study the stochastic quantization of Non-Abelian Antisymmetric Tensor Fields as Reducible Gauge Theories. Then we prove that the fictitious time divergent longitudinal component reproduces the so-called Faddeev-Popov ghost effects from 1-loop contributions. (author)

[en] A project to treat dynamical Wilson fermion in an exact manner is reported. An algorithm for this purpose is briefly described and numerical results for SU(3) and U(1) on 4⁴ are presented. Comparison with the bush-factorized algorithm is done and they agree reasonably with each other. Indications of first order phase transitions are observed near β=5.3 and k=0.14 with 3 flavors for SU(3) and near β=0.9 and k=0.17 with 1 flavor for U(1). (orig.)

No abstract available

[en] An attempt is presented to describe the inclusive spectra of the Δ⁺⁺(1236) by the production mechanism where the Δ⁺⁺ is the decay product of a diffractively produced system. By the use of the Mueller-Regge formalism and the Breit-Wigner formula, various characteristics of the Δ⁺⁺ are well reproduced in terms of the intermediate production of N (1780), N (1860) and N (1990), in addition to N (1470) and N (1688) whose signals were clearly seen in the experimental (Δ⁺⁺π^-) mass distribution. (auth.)